Printing



` centrated to a strength of about '75% solids, at

Patented June 16, 1936.

PRINTING Valentin Dietz, Cologne, Germany, assignor to Erwin B. Elliott and Maurice C. Boyd, Miami,

Fla.

Application January 6, 1933, Serial No. 650,381 Y In Germany October 11, 1932 My present invention pertains to improvements and betterments in the methods and processes of printing from gelatin and analogous films or strata, and, among other things, aims to increase the number of prints which can be secured from `such gelatinous members, to improve the quality of theprinted matter, to make the procedure so simple that inexperienced persons can perform it with facility and success, and to provide a method which can be practised at small cost and with a simple printing mechanism'or even by hand.

In the accompanying drawing the present invention has been illustrated more or less dial grammatically, and in this drawing- Figure 1 shows the soaking of the gelatin film in a bath of glycerine, water, oxgall, para-phenylenediamine, and urotropine;

Figure 2 illustrates the film removed from the bath and its surface dried;

Figure 3 illustrates a sheet of paper bearing. on its surface the image to be printed in a material capable of tanning the gelatin;

Figure-4 shows the paper applied to the surface of the gelatin; i

Figure 5 shows the gelatin iilm4 with the paper removed and the gelatin film tanned;

Figure 6 shows the inking of the printing surface of the tanned film;

Figure 7 -illustrates the printing operation;

Figure 8 presents a modified way of applying the gelatin tanning medium;

Figure 9 shows the process carried out in connection with the dry gelatin film;

Figure 10.shows the swelling of the gelatin -:lm -thus treated; and

Figure 11 sets forth another way of practising the process.

The present preferred perfomance comprises soaking a dry, gelatin-coated, celluloid lm in a bath of glycerin, water, and bile or ox-gall in the approximate proportion by weight of '75% pure glycerine, 24% water, and 1% bile or ox-gall, conwhich concentration such bile or ox-gall is in the form of a sticky paste, but it is to be understood thatit can be employed in powdered form if preferred, -account o f course being taken of its greater concentration.

The coated film is allowed to remain in such bath for about 15 minutes, the period, of course,

depending upon the temperature -of the bath,

whereupon it is withdrawn from the bath and the excess solution removed from the gelatin surface (see Figure 2f), but'such surface drying does not eliminate the swelled-.characteristics of the gelatin which have been brought about by the action of the glycerine and water.

Stated somewhat diierently, the treated gelatin stratum' although swollen and containing water, may be said to have a dry surface. as dis- 5 tinguished from other swollen gelatins which are used'for printingwith wetted surfaces.

Instead ofv using a gelatin coating, a similar stratum of albumen, agar-agar, or other equiva- Y lent colloidal or Vgelatinous substance capable of. 10

swelling in water may be used, and the backing or support instead of being celluloid may be waterproof-paper, glass, or any other suitable medium, which may be transparent, translucent,

or opaque, although I have found in practice that 15. a white celluloid lm is the best choice because it readily discloses an undesired ink smear thereon when taken up for use.

Hereinafter the term fgelatinous has been used to designate any of the specified materials or their equivalents.

The matter to be reproduced is written or printed or otherwise applied to a sheet of paper or its equal by means of an ink containing an ingredient which has the capacity for tanning, shrinking, hardening, rendering water-insoluble or water non-distensible those parts of the swollen film with which it comes in contact (see-Figure 3).

The term tanning" used below in reference to the gelatine is intended to have the meaning that 30 the gelatin is modified in the stated ma'nner'im` mediately above referred to.

Almost all metal salts can be used for this tan ning purpose, including iron chloride, which is particularly powerful for accomplishing this re- 35.

sult, especially due to the facility with which'it penetrates to the base of the gelatine stratum, but such chloride cannot well be used in some cases because it is excessively corrosive.

Nitrates and sulfatos in general are preferred; 40 for example, alum or aluminum sulfate may be employed to about 5% to 10% by weight of the water-soluble ink used, and in case a nitrate isv employed, it is desirable to use about 5% of the weight of the ink. Tannln is also a gelatin-fixing and all of such salts should be used in a normal crystallized form.

Such style of ink may be availed of in any approved manner, for instance, as the ink of an inked ribbon on a typewriter, or the gelatin-fixing agent or agents may be employed as ingredients of the dry coating of a, typewriter paper ribbon or sheet through which the printing is accomplished, or the needed ixing chemical may be used in any other way to reach the desired result. s

The matter to be reproduced having been thus written or printed on a sheet of paper, the face of the latter displaying such matter is applied to and pressed on the unwetted surface of the swollen gelatin stratum (see Figure 4), and in a short time, say two or three minutes, more or I less, the specified xing agent or agents will have caused those portions of the gelatin layer which it or they have contacted to become tanned, hard, firm, and water-insoluble, and also incapable of being swollen in water, and the paper is removed from the face of the gelatin (see Figure 5).

Stated in other words, the one or more xing or hardening ingredients shrink `or condense the portions of the gelatin layer with which they come in contact, thus forming a. somewhat depressed image in the surface of the gelatin.

The glycerne-water-bile mixture makes the gelatin layer ink repellent throughout its thickness,` but the former ink-repellent quality of those parts of such layer as have been hardened and shrunk by the one or more iixing ingredients is overcomeor neutralized so that such parts will readily accept the printing ink when applied thereto.

The dry or unwetted surface of such swollen stratum is then inked, the ink clinging to the hardened and set portions of it, but being repelled by the other parts so that [the ink does not cleave to them (see Figure 6).

-Then `this inked, unwetted, swollen gelatin layer is used as 'a printing element, and, when a sheet of paper is pressed on it by hand or by machine, the ink on the gelatin' surface is transfer-red to the paper as in the usual printing operation (see Figure'7) whereby the printed sheet is an exact reproduction of the original sheet printedl with the specially-prepared ink.

`The glycerine and water mixture which swells the gelatin also acts in a measure as an ink repellent, as does the bile or ox-gall, but one particularly advantageous feature of the bile is that it so -toughens the swollen gelatin that many prints may be taken therefrom without injury to the gelatin stratum, and such toughening does not substantially vreduce or diminish the swollen propertiesl of the layer.

Instead of using the bile or ox-gall with glycerine and water, it may be employed with glycol as aswellirg agent, in which case the mixture would be approximately by weight: glycol 99%, bile or ox-gall 1% (75% solids). e

One of the particular advantages of this process resides in the fact that there is no necessity for wetting the surface of the swollen gelatin layer or resoaking it in water and/or glycerine or glycol during the printing operation, and for that reason alighter pressure and a thinner ink can-be used than has heretofore been cus` tomary in similar processes.

It has beendiscovered that, due to the continued application of the inking-roller over the unwetted surface of the gelatin stratum, an@ hv reason of the repeated pressing of the print paper on the gelatin surface, the bile, ox-gall, or its equivalent which contributes substantially to the ink-repellency ofthe gelatin is gradually and progressively removed or abstracted from 5 the gelatin.

Even though this increasing or developing surface depletion or exhaustion of the incorporated ink-repellent bile may in a measure be overcome or replaced by the ink-repellent in the body of 1o the gelatin layer working its way to the surface, it has been found that it is desirable to replace such abstracted or withdrawn .material continuously to permit it to be present in the gelatin lm at all times substantially in its full or relquired amount.

lent to be used in the ink cannot always be stated 25.

with accuracy because the quantity to be mixed in the ink depends in material measure upon the nature and quality of the color employed and upon the grade and consistencyI of the linseedoil-varnish. o

The correct proportion of such ink-repellent to be mixed or combined with the ink can, however, be comparatively easily determined by simple tests, bearing in mind that if too little is used the gelatin layer will be gradually starved 35 of its repellent, which effect will be indicated by the character of the prints; whereas if too much is put in the ink, the ink will not properly adhere to those sections of the gellatin layer to which it should cleave.

Thus, for each application of ink, a suitable supply of the ink-repellent is simultaneously made to the surface of the gelatin stratum, which either' prevents the withdrawal of such repellent from the gelatin or replaces that which maybe abstracted, but, in either case, the result is the` same in that the gelatin is at alltimes in proper condition for printing and does not become exhausted or deprived of any of its essential constituents.

The ink-repellent used acts not only to make the condition of the gelatin such that it will not receive the ink, but it also renders the swollen gelatin layer ilrmer and tougher than has heretofore been possible, and, accordingly, such gelatin stratum can' be used for producing a large number of prints of the highest quality. Seemingly, both the glycerine or glycol and the bile or ox-gall tend to give the swollen portions of the gelatin substantially improved wearing quali- 6o' as by the old wet process there is a distinct tendency to cause it to become somewhat rough.

The specified bile or ox-gall when incorporated in the ink has the further advantage of causing -the ink to dry and harden rapidly, so that danger y siderable number of prints is required, but, in

those 'cases where a comparatively small number of prints sumces, the ink-repellent may be incorporated in the gelatin stratum alone or in the ink alone.

'I'he most available form of bile is the wellknown ox-gall, the principal ingredients of which are sodium glycocholate and sodium taurocholate, and while it is somewhat difficult and more or less expensive to separate such salts from one an- .that a corrspondingly different quantity would be required because of the dry form used.

In order to increase the intensityv of the gelatin-fixing when an inked ribbon is employed, about one to two per cent of urotropine may be added to the repellent in the gelatin layer or may b`e wiped over thesurface of the gelatin stratum, and when it comes in contact with an acid salt it breaks down into ammonia and formaldehyde, the latter being an intense hardening agent (see Figure 1). A

Instead of incorporating the gelatin fixing or setting ingredient in the ink employed in printing the master sheet which is subsequently applied to the swollen gelatin surface, the printing may be done on such sheet with any 'suitable medium which remains fresh or moist at least temporarilmand then the gelatinvxing or setting agent in the form of a powder may be sprinkled over such printed matter to 'which it adheres (see Figure 8), and then' such sheet is transferred to the gelatin surface as indicated hereinbei'ore.

As a modification of this process, but not quite so simple as the method described above. the

original gelatin layer may be swollen with glycerine and water, or with glycol, and then after the gelatin s'tratlun has been tanned or set by the matter to be printed, either the layer may be soaked in a hath containing any of the atreve specified ink-repellents, the excess removed fram the surface, and the printing performed as tri-- dicated above; or the ink containing the inirepellent may be used on the swollen layer without such soaking, or both of these procedures may be, employed conjointly.

In some instances, it may be'feasible to apply the matter to be printed with any one or more of the specified gelatin-fixing chemicals to the surface of a vgelatin stratum dry .throughout its thickness, either directly or'rst ona sheet of paper which is then pressed on the surface (see Figure 9), and then swelling the stratum, as, for example, by the use of steam (see Figure 10) and thereupon proceeding as indicated above.

If desired,such original bone-dry stratum may have `any one or moreof the ink-repellent agents incorporated in it before the gelatin-fixing operation takes place.

In some case-s where the fixing of thecomp1ete ly dry stratum takes place it may be desirable to wipe over the 'surface of the gelatin layer with water before it is subjected yto the further use of a moistening'agent. 5 Still afiother way of employing the invention is to cut the matter to be reproduced in a typewriter without an ink-ribbon in a wax or other appropriate stencil, so that the typewritten letters cut through the -wax or its equivalent. 10 Then such stencil is laid on the surface of the swollen gelatin layer containing the one or more bile salts and an absorbent sheet impregnated Awith full strength formaldehyde is superposed on top of the sgencil and rolled o r pressed thereon so 15 that the fo maldehyde acting on the underlying gelatin through the cut matter of the stencil tans, sets, or hardens such portions only of the gelatin (see Flgurell). l

Thereupon, the absorbent sheet and the stencil 20 are removed andthe gelatin layer used for printing. as indicated above.

By this procedure the Wax or the like of the stencil prevents the action of the setting formaldehyde from spreading, with the result `that well-defined, clear-cut letters are fixed in the gelatin.

Of course, such original gelatin layer need not necessarily be impregnated with the one or more bile salts, as they may be used solely in the ink, if preferred, or theiruse may in some cases be dispensed with.

The term ink-repellen as herein applied to the bile, ox-gall, or bile salts has been employed with the meaning that the specified material performs the function of augmenting or reenforcing the capacity of the swollen gelatin stratum to reject the applied ink and to preserve-and to prolong indefinitely the property of the distended gelatin to repel the ink, thus permitting the gelatin stratum to be used with its unwetted surface during any printing operation and-over the entire service period of the layer. V

The invention, as specied in the following claims, is not restricted to the precise details of procedure set forth hereinabove, and those'skilled in this art will' readily appreciate that more or less major and minor modifications may be resorted to.

For example, when any of the foregoing proceases are practiced under somewhat dry or warm atmospheric conditions, it is desirable to use an amine, such as ethylenediamine, para-phenylenediamine, or alpha-naphthylamine, as an ingredient of the water-glycerine-bile bath solution (lee Figure 1), or it may be applied to the surface of the galatinous layer before inking (so y that it will be absorbed by such'surface), or it may be employed as an ingredient of the ink. In the first instance, one-quarter of one per cent is added to the water-glycerine-bile solution, or in the second example approximately one-quarter of one per cent solution is used for the surface application, or in the third case about one per cent is added to the ink, all of these proportions making the layer ink-repellent by an agent other in agreement with the image to be printed. f f

2. In the art of printing, swelling a suitablysupported gelatinous layer and at the same time making the layer ink-repellent by an agent other l than the swelling medium but incorporated in said medium and including an amine, and tan- `ning the parts of such layer in agreement with Y the image to be printed by a tanning medium incorporating iron chloride.

3. In the art of printing, swelling a suitably-,- supported gelatinous layer and at the same time making the layer ink-repellent by an agent other than the swelling medium but incorporated in ,said medium and including anamine, and tanning the parts of said layer in agreement with the image to be printed by a tanning medium incorporating iron chloride and urotropine.

4. In the art of printing, swelling a suitablysupported gelatinous layer and at the same time making the layer ink-repellent by an agent other than the swelling medium but incorporated in said medium and including an amine, and tan- -ning the parts of said layer in agreement with the image to be printed by a tanning medium incorporating aluminum sulfate.

5. In the art of' printing, swelling a suitablysupported gelatinous layer and at the same time making the layer ink-repellent by an agent other than the swelling medium but incorporated in f 4 said medium and including an amine, and tanning the parts o1 said layer in agreement jwith the image to be printed by a tanning medium incorporating aluminum sulfate and urotropine. 6. In the art of printing, swelling a suitably supported gelatinous layer and at the same time making the layer ink-repellent by an agent other than the swelling medium but incorporated in said medium and including an amine, and tanning the parts of said layer in agreement with the image to be printed by a tanning medium incorporating alum.

7. In the art of printing, swelling a suitablysupported gelatinous/layer and at the same time making the layer ink-repellent by an'agent other 20 than `,the swelling medium but incorporated in said medium and including an amine, and tanning the parts of said layer in agreement with the image to be printed by a tanning medium incorporating alum and urotropine.

VALENTm' DIETZ. 

